1. Field of the Invention
The invention relates to a sensor for detecting the direction and intensity of solar insolation, particularly, for controlling an air conditioning system.
2. Description of Related Art
Sensors of this type, for detecting the solar insolation in a motor vehicle interior, are used to control an air conditioning system to compensate for increased temperature in the vehicle interior resulting form the incoming solar insolation. To control precisely the temperature of the vehicle interior with the aid of the air conditioning system, the heating up of the passenger compartment due to the action of the solar insolation has to be determined with the aid of the sensor. Since the sensor elements detect the incident light radiation in different directions, the air conditioning system can be fed a corresponding, individual measurement signal to control the temperature in the vehicle interior differently at certain locations. It is thus possible to obtain different air conditions in the vehicle interior matched to the individual vehicle occupants'desires, for example, one condition on the driver side and another on the front-passenger side and/or on the front seats versus the rear seats.
A sensor similar to this type is disclosed in DE 38 21 743, in which a sensor has two photodiodes, one being assigned to each of the left-hand and right-hand sides of the vehicle, respectively. The photodiodes also are arranged on a face of the sensor whose surfaces can be subjected to the solar insolation coming in from the left-hand and right-hand sides of the vehicle, respectively. The direction of the solar insolation, therefore, can be determined.
Moreover, a temperature sensor is provided in the center between the two photodiodes. The temperature sensor is constantly subjected to the solar insolation because of its central arrangement or location. As a result, the incident heat can be detected and a variation in the temperature of the photodiodes can be compensated for. A disadvantage of this known sensor is that it is relatively complex and complicated and is therefore not cost effective. The evaluation of the photodiode signals is relatively complex. Moreover, photodiodes age and a permanent load due to solar insolation has a negative effect.